CN107614476B

CN107614476B - Method for producing allyl acetate

Info

Publication number: CN107614476B
Application number: CN201680029957.6A
Authority: CN
Inventors: 向吉惠; 岩间康拓
Original assignee: Showa Denko KK
Current assignee: Lishennoco Co ltd; Resonac Holdings Corp
Priority date: 2015-06-29
Filing date: 2016-06-09
Publication date: 2020-11-17
Anticipated expiration: 2036-06-09
Also published as: JPWO2017002576A1; CN107614476A; TWI621610B; WO2017002576A1; JP6366841B2; TW201718457A

Abstract

The purpose of the present disclosure is to suppress catalyst degradation after a long-term reaction and to increase the life of a catalyst when allyl acetate is produced by a reaction of oxygen, acetic acid, and propylene. In one embodiment of the present disclosure, allyl acetate is produced by a vapor phase catalytic oxidation reaction by supplying propylene, oxygen, and acetic acid as raw material gases to a fixed-bed tubular reactor packed with a catalyst for producing allyl acetate containing (a) palladium, (b) gold, (c) a 4 th-cycle metal compound having at least 1 element selected from copper, nickel, zinc, and cobalt, (d) an alkali metal salt compound, and (e) a carrier, in the above production method, 2 or more catalyst layers containing the catalyst for producing allyl acetate are disposed along the flow direction of the raw material gas in the reaction tube of the fixed-bed tubular reactor so that the amount of the (d) alkali metal salt compound supported on the (e) carrier decreases in the order from the inlet side to the outlet side of the fixed-bed tubular reactor, and the amounts of the (d) alkali metal salt compound in the catalysts for producing allyl acetate contained in the respective catalyst layers are different.

Description

Method for producing allyl acetate

Technical Field

The present invention relates to a process for producing allyl acetate by gas-phase catalytic oxidation of propylene, oxygen and acetic acid.

Background

Allyl acetate is one of important industrial raw materials useful as a solvent, a raw material for producing allyl alcohol, and the like.

Methods for producing allyl acetate include a method using propylene, acetic acid, and oxygen as raw materials and using a gas phase reaction or a liquid phase reaction. As a catalyst used for this reaction, a catalyst in which palladium is used as a main catalyst component, an alkali metal and/or alkaline earth metal compound is used as a co-catalyst, and these are supported on a carrier is widely known and used. For example, japanese patent application laid-open No. 2-91045 (patent document 1) discloses a method for producing allyl acetate using a catalyst in which palladium, potassium acetate, and copper are supported on a carrier.

Although the product is different from allyl acetate, for example, japanese unexamined patent publication No. 2003-525723 (patent document 2) discloses a method for producing a catalyst for vinyl acetate production in which palladium is supported in a first step, gold is supported in a second step, reduction treatment is performed, and then copper (ii) acetate and potassium acetate are supported in a third step, thereby suppressing the production of carbon dioxide, in the production of vinyl acetate using ethylene, oxygen and acetic acid as starting materials.

In the vinyl acetate production process using the above catalyst, a gas phase reaction using a catalyst uniformly packed in a fixed bed multitubular reactor is generally used in many cases. On the other hand, U.S. Pat. No. 8907123 (patent document 3) also discloses the following method: in order to suppress the occurrence of hot spots (hotspots) in the catalyst layer in the reaction tube, catalysts having different activities are distributed in a layered manner from the inlet toward the outlet of the reaction tube in the reactor, and are filled so that the catalyst activities are sequentially increased toward the outlet of the reaction tube.

In a typical vinyl acetate production process using the above catalyst, if a continuous reaction is carried out for a long period of time of several thousand hours, potassium acetate flows out little by little from the reaction tube during the process operation, and therefore it is necessary to continuously supply potassium acetate to the catalyst, which is described in japanese patent laid-open nos. 2-91045 (patent document 1) and シリーズ "catalyst と", "" (series of "catalyst and economy" description), vol.35, No.7(1993), and 467 to 470 (non-patent document 1).

In an allyl acetate manufacturing process, the reaction is carried out at a lower acetic acid concentration than in a vinyl acetate manufacturing process. For example, Japanese patent laid-open No. 2-91045 (patent document 1) and International publication No. 2009/142245 (patent document 4) describe that the proportion of acetic acid in the raw material gas is preferably 6 to 10 vol%. In contrast, in the vinyl acetate production process, the proportion of acetic acid in the raw material gas is preferably 7 to 40% by volume, as described in, for example, japanese patent laid-open No. 2003-212824 (patent document 5).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2-91045

Patent document 2: japanese Kokai publication 2003-525723

Patent document 3: specification of U.S. Pat. No. 8907123

Patent document 4: international publication No. 2009/142245

Patent document 5: japanese patent laid-open publication No. 2003-212824

Non-patent document

Non-patent document 1: シリーズ catalyst 3632, Vol.35, No.7(1993), 467-470 page "supporting expansion of Oxalic acid ビニルプロセス" (the transition and expansion of vinyl acetate process ")

Disclosure of Invention

Problems to be solved by the invention

However, the conventional method described in patent document 1 has a problem that the catalyst on the outlet side of the reactor deteriorates remarkably quickly.

The present invention has been made in view of the above circumstances, and an object thereof is to suppress catalyst deterioration in the case of producing allyl acetate by a reaction of oxygen, acetic acid, and propylene, when the reaction is performed for a long time, and to achieve a long life of the catalyst.

Means for solving the problems

The inventor of the present invention finds, through research and results, that: the outflow rate of an alkali metal salt compound such as potassium acetate depends on the concentration of acetic acid in the reactor; and, the concentration of acetic acid in the reaction on the outlet side of the reactor is significantly reduced as compared with the inlet side of the reactor, so that the supplied alkali metal salt compound is accumulated in the catalyst on the outlet side of the reactor, and the deterioration of the catalyst is significantly accelerated. In addition, it was found that: in the allyl acetate production catalyst, in contrast to the vinyl acetate production catalyst, the initial activity of the catalyst increases as the amount of the alkali metal salt compound supported on the carrier increases, and by arranging 2 or more catalyst layers having different amounts of the alkali metal salt compound in the reaction tube of the fixed-bed tubular reactor along the reaction direction so that the amount of the alkali metal salt compound supported on the carrier decreases in order from the inlet side to the outlet side of the fixed-bed tubular reactor, the concentration gradient of the alkali metal salt compound is reduced, local catalyst degradation is suppressed, and as a result, the performance of the catalyst can be effectively exhibited. Patent document 3 also discloses an example in which the concentration of the alkali metal salt compound in the catalyst for vinyl acetate production is set so as to decrease sequentially toward the outlet side of the fixed-bed tubular reactor, but this is for increasing the catalytic activity toward the outlet side of the reaction tube, and the technical idea underlying this is contrary to the technical idea of the present invention of suppressing the deterioration of the catalyst at the outlet side of the reaction tube and extending the life of the catalyst.

Namely, the present invention relates to the following [1] to [8 ].

[1]

A process for producing allyl acetate, characterized by supplying propylene, oxygen and acetic acid as raw material gases to a fixed-bed tubular reactor packed with an allyl acetate production catalyst comprising (a) palladium, (b) gold, (c) a 4 th-cycle metal compound having at least 1 element selected from copper, nickel, zinc and cobalt, (d) an alkali metal salt compound and (e) a carrier, and producing allyl acetate by a vapor-phase catalytic oxidation reaction, wherein 2 or more catalyst layers containing the allyl acetate production catalyst are arranged in the reaction tube of the fixed-bed tubular reactor along the flow direction of the raw material gases so that the amount of the (d) alkali metal salt compound supported on the (e) carrier decreases in the order from the inlet side to the outlet side of the fixed-bed tubular reactor, and the amounts of the (d) alkali metal salt compound in the allyl acetate production catalysts contained in the respective catalyst layers differ from each other .

[2]

The process for producing allyl acetate according to [1], wherein the amount (g) of the alkali metal salt compound (d) supported by the catalyst layer on the inlet side of the reaction tube per 1g of the (e) carrier is 1.2 to 3.0 times the amount (g) of the alkali metal salt compound (d) supported by the catalyst layer on the outlet side per 1g of the (e) carrier.

[3]

The process for producing allyl acetate as described in [1] or [2], wherein the reaction tube is a straight tube, the catalyst layer is 2 layers, and the ratio of the lengths of the catalyst layer on the inlet side and the catalyst layer on the outlet side of the reaction tube in the flow direction of the raw material gas is 4:1 to 1: 4.

[4]

The method for producing allyl acetate according to any one of [1] to [3], wherein the fixed-bed tubular reactor is a multitubular type.

[5]

The method for producing allyl acetate according to any one of [1] to [4], wherein the alkali metal salt compound (d) is at least 1 selected from potassium acetate, sodium acetate and cesium acetate.

[6]

The method for producing allyl acetate according to any one of [1] to [5], wherein the (c) 4 th cycle metal compound is a compound having copper or zinc.

[7]

The method for producing allyl acetate according to any one of [1] to [6], wherein the (c) 4 th cycle metal compound is copper acetate.

[8]

The method for producing allyl acetate according to any one of [1] to [7], wherein the catalyst for producing allyl acetate has a mass ratio of (a) palladium, (b) gold, (c) a 4 th cycle metal compound to (d) an alkali metal salt compound of (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.00125-22.5: 0.02-90: 0.2 to 450.

Effects of the invention

According to the method for producing allyl acetate of the present invention, the catalyst life is extended. As a result, by using this production method, the production cost of allyl acetate can be reduced, and allyl acetate can be efficiently produced.

Drawings

Fig. 1A is a schematic view showing a filling position of the catalyst of example 1.

Fig. 1B is a schematic diagram showing the filling position of the catalyst of comparative example 1.

Fig. 1C is a schematic diagram showing the filling position of the catalyst of comparative example 2.

Detailed Description

The following description is of preferred embodiments of the present invention, but the present invention is not limited to these embodiments, and it is intended to be understood that the present invention can be variously applied within the spirit and scope thereof.

In the present invention, 2 or more catalyst layers containing an allyl acetate production catalyst are arranged in the reaction tube of a fixed-bed tubular reactor along the flow direction (reaction direction) of a raw material gas: the amount of the alkali metal salt compound supported on the carrier decreases in the order from the inlet side to the outlet side of the fixed-bed tubular reactor, and the amount of the alkali metal salt compound in the allyl acetate production catalyst contained in each catalyst layer differs.

< catalyst >

The catalyst for producing allyl acetate used in the present invention contains the following components: (a) palladium, (b) gold, (c) a 4 th-cycle metal compound having at least 1 element selected from the group consisting of copper, nickel, zinc and cobalt, (d) an alkali metal salt compound and (e) a carrier. These components are explained below.

(a) Palladium (II)

In the present invention, palladium (a) may have any valence number, but is preferably metallic palladium. The "metallic palladium" in the present invention means palladium having a valence of 0. The metallic palladium can be usually obtained by reducing 2-valent and/or 4-valent palladium ions with hydrazine, hydrogen gas, or the like as a reducing agent. In this case, not all of the palladium may be in a metallic state.

The raw material of palladium is not particularly limited, and metallic palladium or a palladium precursor capable of being converted into metallic palladium may be used. Examples of the palladium precursor include palladium chloride, palladium nitrate, palladium sulfate, sodium chloropalladate, potassium chloropalladate, barium chloropalladate, palladium acetate and the like. Sodium chloropalladate is preferably used. The palladium precursor may be used as a single compound or as a combination of a plurality of compounds.

The mass ratio of (a) palladium to (e) carrier in the catalyst for producing allyl acetate is preferably (a): (e) 1: 10-1: 1000, more preferably (a): (e) 1: 20-1: 500. the ratio is defined as the ratio of the mass of the palladium element to the mass of the support.

(b) Gold (Au)

In the present invention, the (b) gold is supported on the carrier in the form of a compound containing the gold element, but it is preferable that substantially all of the gold is finally metallic gold. The "metallic gold" in the present invention means gold having a valence of 0. Metallic gold can be generally obtained by reducing 1-valent and/or 3-valent gold ions with hydrazine, hydrogen gas, or the like as a reducing agent. In this case, not all gold may be in a metallic state.

The raw material of gold is not particularly limited, and metallic gold or a gold precursor capable of being converted into metallic gold may be used. Examples of the gold precursor include chloroauric acid, sodium chloroaurate, potassium chloroaurate, and the like. Chloroauric acid or sodium chloroaurate is preferably used. The gold precursor may be used as a single compound or as a combination of a plurality of compounds.

The mass ratio of (b) gold to (e) support in the catalyst for producing allyl acetate is preferably (b): (e) 1: 40-1: 65000, more preferably (b): (e) 1: 550-1: 32000, more preferably (b): (e) 1: 750-1: 10000. the ratio is defined as the ratio of the mass of the gold element to the mass of the carrier.

The amount of (b) gold in the catalyst for allyl acetate production is preferably 0.125 to 2250 parts by mass, more preferably 0.25 to 14 parts by mass, and still more preferably 0.8 to 10 parts by mass, based on 100 parts by mass of palladium. The parts by mass of gold and palladium are based on the mass of the respective elements. By setting the amount of gold to such an amount, maintenance of the activity of the catalyst in the allyl acetate-generating reaction and allyl acetate selectivity can be obtained in a well-balanced manner.

(c) Periodic 4 metal compound having at least 1 element selected from copper, nickel, zinc and cobalt

In the present invention, as the (c) 4 th cycle metal compound, a soluble salt such as a nitrate, a carbonate, a sulfate, an organic acid salt, a halide or the like of at least 1 element selected from copper, nickel, zinc and cobalt can be used. The 4 th cycle metal compound is preferably a compound having copper or zinc from the viewpoint of further improving the catalyst activity. Examples of the organic acid salt include acetate. In general, compounds that are readily available and water soluble are preferred. Preferred examples of the compound include copper nitrate, copper acetate, nickel nitrate, nickel acetate, zinc nitrate, zinc acetate, cobalt nitrate, and cobalt acetate. Among these, copper acetate is most preferable from the viewpoint of stability of raw materials and availability. The metal compound of the 4 th cycle can be used alone or in combination of two or more.

The mass ratio of the (c) 4 th cycle metal compound to the (e) carrier in the catalyst for producing allyl acetate is preferably (c): (e) 1: 10-1: 500, more preferably (c): (e) 1: 20-1: 400. the ratio is defined as the ratio of the combined mass of the elements copper, nickel, zinc and cobalt to the mass of the support.

(d) Alkali metal salt compound

In the present invention, as the (d) alkali metal salt compound, hydroxides, acetates, nitrates, bicarbonates of lithium, sodium, potassium, rubidium, cesium, and the like can be used. Preferred are potassium acetate, sodium acetate and cesium acetate, and more preferred are potassium acetate and cesium acetate. The alkali metal salt compound may be used alone or in combination of two or more.

The mass ratio of (d) the alkali metal salt compound to (e) the carrier in the catalyst for producing allyl acetate is preferably (d): (e) 1: 2-1: 50, more preferably (d): (e) 1: 3-1: 40. the ratio is defined as the ratio of the mass of the alkali metal salt compound to the mass of the carrier.

(e) Carrier

The carrier (e) used in the present invention is not particularly limited, and a porous material generally used as a carrier for a catalyst can be used. Examples of preferred supports include silica, alumina, silica-alumina, diatomaceous earth, montmorillonite, titania and zirconia. More preferably, silicon dioxide is used. When a substance containing silica as a main component is used as the carrier, the silica content in the carrier is preferably at least 50% by mass, more preferably at least 90% by mass, relative to the mass of the carrier.

The carrier preferably has a specific surface area of 10 to 1000m as measured by the BET method²A range of/g, particularly preferably 100 to 500m²(ii) a range of/g. The bulk density of the carrier is preferably in the range of 50 to 1000g/L, and particularly preferably in the range of 300 to 500 g/L. The water absorption of the carrier is preferably 0.05 to 3g/g, and particularly preferably 0.1 to 2 g/g. As for the microporous structure of the support, the average pore diameter thereof is preferably in the range of 1 to 1000nm, particularly preferably in the range of 2 to 800 nm. If the average pore diameter is less than 1nm, gas diffusion may be difficult. On the other hand, if the pore diameter is larger than 1000nm, the specific surface area of the carrier becomes too small, and the catalyst activity may be lowered.

The water absorption of the carrier in the present invention means a value measured in the following order.

1. About 5g of the carrier was precisely weighed by a balance and placed in a 100cc beaker. The mass at this time was denoted as w₁。

2. About 15mL of pure water (ion-exchanged water) was added to the beaker to completely cover the support.

3. The mixture was left to stand for 30 minutes.

4. The upper clear pure water was removed from the carrier.

5. The water adhered to the surface of the carrier is removed by lightly pressing with a paper towel or the like until the surface is not glossy.

6. The total mass of the carrier and the pure water was precisely weighed. Let the mass at this time be w₂。

7. The water absorption of the carrier was calculated from the following formula.

Water absorption (g/g-carrier) ═ w₂-w₁)/w₁

Therefore, the water absorption amount (g) of the carrier is calculated by the water absorption rate (g/g-carrier) x mass (g) of the carrier used.

The shape of the support is not particularly limited. Specifically, the particles may be in the form of powder, spheres, granules, etc., but are not limited thereto. The most suitable shape can be selected in accordance with the reaction form, the reactor, and the like used.

The size of the particles of the carrier is also not particularly limited. When the carrier is spherical, the particle diameter is preferably in the range of 1 to 10mm, more preferably in the range of 2 to 8 mm. When a gas phase reaction is carried out by filling a tubular reactor with a catalyst, if the particle diameter is less than 1mm, a large pressure loss is generated when a gas is circulated, and there is a possibility that effective gas circulation cannot be carried out. On the other hand, if the particle diameter is larger than 10mm, the reaction gas is less likely to diffuse into the catalyst, and the catalytic reaction may not be efficiently performed.

(f) Alkali solution

The alkali solution (f) used in step 2 of the catalyst production step described below is not particularly limited, and any alkali solution can be used. Examples of the raw material of the alkali solution include alkali compounds such as hydroxides of alkali metals or alkaline earth metals, bicarbonates of alkali metals or alkaline earth metals, carbonates of alkali metals or alkaline earth metals, and silicates of alkali metals or alkaline earth metals. The alkali metals are preferably lithium, sodium, and potassium, and the alkaline earth metals are preferably barium and strontium. Particularly preferred examples of the alkali compound include sodium metasilicate, potassium metasilicate, sodium hydroxide, potassium hydroxide, and barium hydroxide. By contacting with the alkali solution, part or all of the palladium compound and part or all of the gold compound can be converted into an oxide or a hydroxide.

The basic compound is used in an excess amount, as appropriate, based on the total of (a) palladium and (b) gold in terms of molar equivalents. For example, the amount of the basic compound used corresponds to the total of preferably 1 to 3 moles, more preferably 1.2 to 2.5 moles per 1 mole of (a) palladium and preferably 2 to 10 moles, more preferably 3 to 8 moles per 1 mole of (b) gold.

The solvent for forming the alkali solution is not particularly limited, and water, methanol, ethanol, and the like are preferable examples.

< Process for producing catalyst >

The catalyst production step is not particularly limited as long as the components (a) to (d) can be supported on the carrier (e), but the catalyst production step is preferably carried out in the following steps.

Step 1. preparation of a homogeneous solution containing a palladium raw material and a gold raw material, and contacting and impregnating the resulting homogeneous solution with (e) a carrier to thereby support the palladium raw material and the gold raw material on the carrier

Step 2. step of impregnating the carrier obtained in step 1 with (f) an alkali solution in contact therewith

Step 3. step of subjecting the carrier obtained in step 2 to reduction treatment, and

step 4. supporting (c) the 4 th cycle metal compound and (d) the alkali metal salt compound on the carrier obtained in step 3

Next, each step will be explained.

Step 1

In this step, a homogeneous solution containing a palladium raw material (metallic palladium or a precursor thereof) and a gold raw material (metallic gold or a precursor thereof) is prepared, and the carrier is impregnated with the homogeneous solution to carry these raw materials. The support of these raw materials on the carrier is preferably in a so-called "eggshell type". In this case, the method for supporting the homogeneous solution containing the palladium raw material and the gold raw material on the carrier is not particularly limited as long as the eggshell-type supported catalyst can be obtained as a result. The eggshell-type supported catalyst refers to a supported catalyst in which most of the active component is present on the outer surface of the carrier particle or the molded body, depending on the distribution state of the active component (for example, metallic palladium) in the carrier particle or the molded body. Specific examples of the method for producing the eggshell-type supported catalyst include a method in which the raw material is dissolved in an appropriate solvent such as water or acetone, or an inorganic acid or an organic acid such as hydrochloric acid, nitric acid, or acetic acid, or a solution thereof, and is directly or indirectly supported on the surface layer of the carrier. The method of directly supporting the carrier includes an impregnation method and a spray coating method. As a method for indirectly supporting the palladium material and the gold material, there may be mentioned a method in which a uniform solution containing the palladium material and the gold material is uniformly supported on a carrier (step 1), and then the palladium material and the gold material are moved to the surface by contact impregnation with an alkali solution (step 2) and then reduced (step 3), as described later.

The support of the palladium raw material and the gold raw material on the carrier can be carried out by preparing a uniform solution containing the palladium raw material and the gold raw material and impregnating the solution in contact with an appropriate amount of the carrier. More specifically, the palladium material and the gold material are dissolved in a suitable solvent such as water or acetone, or an inorganic acid or an organic acid such as hydrochloric acid, nitric acid, or acetic acid, or a solution thereof to prepare a uniform solution, and the carrier is impregnated with the uniform solution to obtain the impregnated carrier (a). Drying may be performed after impregnation, but it is preferable to omit the drying step because the step 2 can be further performed without the drying step.

Step 2

This step is a step of impregnating the impregnated carrier (a) obtained in step 1 with an alkali solution (f) in contact therewith to obtain an impregnated carrier (B). The basic substance used in step 2 may be used as it is if it is a liquid, but is preferably supplied in the form of a solution. The base solution is preferably a solution of water and/or alcohol. The contact condition between the impregnated carrier (a) and the alkali solution is not particularly limited, but the contact time is preferably in the range of 0.5 to 100 hours, more preferably in the range of 3 to 50 hours. If the time is less than 0.5 hour, sufficient performance may not be obtained, while if it exceeds 100 hours, the support may be damaged.

The contact temperature is not particularly limited, but is preferably in the range of 10 to 80 ℃ and more preferably in the range of 20 to 60 ℃. If the contact is performed at a temperature lower than 10 ℃, a sufficient switching rate may not be obtained. On the other hand, if the temperature exceeds 80 ℃, aggregation of palladium or gold may be promoted.

Step 3

This step is a step of subjecting the impregnated carrier (B) obtained in step 2 to a reduction treatment. The reduction method may use either one of liquid-phase reduction and gas-phase reduction. The metal-supporting carrier obtained in this step is used as the metal-supporting carrier (C).

The liquid-phase reduction may be carried out in any of a nonaqueous type and a water type using an alcohol or a hydrocarbon. As the reducing agent, carboxylic acid and its salt, aldehyde, hydrogen peroxide, saccharide, polyphenol, boron compound, amine, hydrazine, etc. can be used. Examples of the carboxylic acid and its salt include oxalic acid, potassium oxalate, formic acid, potassium formate, potassium citrate, ammonium citrate and the like. Examples of the aldehyde include formaldehyde and acetaldehyde. Examples of the saccharide include glucose. Examples of the polyhydric phenol include hydroquinone and the like. Examples of the boron compound include diborane and sodium borohydride. Among them, hydrazine, formaldehyde, acetaldehyde, hydroquinone, sodium borohydride, or potassium citrate is preferably used, and hydrazine is more preferably used.

The temperature is not particularly limited when the liquid phase reduction is carried out, but the liquid phase temperature is preferably set to a range of 0 to 200 ℃, more preferably 10 to 100 ℃. If the temperature is lower than 0 ℃, a sufficient reduction rate may not be obtained, while if it exceeds 200 ℃, aggregation of palladium or gold may occur. The reduction time is not particularly limited, and is preferably 0.5 to 24 hours, more preferably 1 to 10 hours. If the time is less than 0.5 hours, the reduction may not be sufficiently performed, while if the time exceeds 24 hours, the palladium or gold may aggregate.

The reducing agent used for the gas phase reduction is selected from olefins such as hydrogen, carbon monoxide, alcohols, aldehydes, ethylene, propylene, isobutylene, and the like. Hydrogen or propylene is preferably used as the reducing agent.

In the case of vapor phase reduction, the temperature is not particularly limited, but the impregnated carrier (B) is preferably heated to a temperature in the range of 30 to 350 ℃, more preferably 100 to 300 ℃. If the temperature is lower than 30 ℃, a sufficient reduction rate may not be obtained; on the other hand, if the temperature exceeds 300 ℃, aggregation of palladium or gold may occur. The reduction time is not particularly limited, and is preferably 0.5 to 24 hours, more preferably 1 to 10 hours. If the time is less than 0.5 hours, the reduction may not be sufficiently performed. On the other hand, if it exceeds 24 hours, aggregation of palladium or gold may occur.

The pressure for the treatment of the gas phase reduction is not particularly limited, but is preferably in the range of 0.0 to 3.0MPaG (gauge pressure), more preferably in the range of 0.1 to 1.0MPaG (gauge pressure), from the viewpoint of facilities.

The supply of the reducing agent during the gas phase reduction is preferably carried out at a space velocity (hereinafter referred to as SV) of 10 to 15000 hours in a standard state^-1Particularly preferably in the range of 100 to 8000 hours^-1Is carried out within the range of (1).

The gas phase reduction may be carried out at various concentrations of the reduced matter, and an inert gas may be added as a diluent as required. Examples of the inert gas include helium, argon, and nitrogen. The reduction may be carried out in the presence of already gasified water by allowing hydrogen, propylene, or the like to be present.

The catalyst before reduction treatment may be packed in a reactor, and allyl acetate may be produced by reducing propylene and then introducing oxygen and acetic acid.

The carrier that has been reduced may also be washed with water as needed. The washing may be carried out in a flow-through manner or in a batch manner. The cleaning temperature is preferably in the range of 5 to 200 ℃, and more preferably in the range of 15 to 80 ℃. The washing time is not particularly limited. It is preferable to select conditions sufficient for removing the remaining, unpreferable impurities. Examples of the undesirable impurities include sodium and chlorine. After cleaning, the mixture may be dried by heating as needed.

Step 4

This step is a step of supporting (C) the 4 th cycle metal compound and (d) the alkali metal salt compound on the metal-supporting carrier (C) obtained in step 3.

A solution containing the necessary amounts of (C) the 4 th cycle metal compound and (d) the alkali metal salt compound and having a mass of 0.9 to 1.0 times the water absorption amount of the carrier is contacted with and impregnated in the metal supporting carrier (C), and the metal supporting carrier (C) is dried to support each compound. The solvent in this case is not particularly limited. Various solvents capable of dissolving the alkali metal salt compound to be used in a solution having a mass of 0.9 to 1.0 times the water absorption amount of the carrier can be used. The solvent is preferably water. In the present invention, the loading amount of the alkali metal salt compound can be adjusted by changing the concentration of the solution. The drying temperature and time are not particularly limited.

< composition of catalyst component >

(a) The mass ratio of (a), (b), (c) and (d) is preferably (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.00125-22.5: 0.02-90: 0.2 to 450, more preferably (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.0025 to 0.14: 0.04-50: 0.4 to 250, particularly preferably (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.008-0.1: 0.04-50: 0.4 to 250. It is preferable that all the catalyst layers satisfy the above mass ratio. Based on the mass of the constituent elements for (a), (b) and (c) and on the mass of the alkali metal salt compound for (d).

The amount of the metal element contained in the catalyst for producing allyl acetate and the composition ratio thereof can be measured by chemical analysis such as high-frequency inductively coupled plasma emission spectrometry (hereinafter, referred to as "ICP"), fluorescent X-ray analysis (hereinafter, referred to as "XRF"), and atomic absorption spectrometry.

Examples of the measurement method include the following methods: a predetermined amount of the catalyst is pulverized in a mortar or the like to obtain a uniform powder, and then the powdery catalyst is added to an acid such as hydrofluoric acid or aqua regia and heated and stirred to be dissolved to obtain a uniform solution, and then the solution is diluted to an appropriate concentration with pure water and quantitatively analyzed by ICP.

< fixed bed tubular reactor >

The "fixed-bed tubular reactor" in the present invention is formed by filling a tubular reaction tube with a catalyst (supported catalyst) as a fixed bed. The reaction substrate is supplied to the reaction tube in a gas phase, and the reaction product is discharged from the outlet of the reaction tube. The tubular reaction tube is preferably a straight tube type from the viewpoints of manufacturing and maintenance of the apparatus, operability at the time of catalyst filling and replacement, removal of reaction heat, and the like. The reaction tube is preferably arranged in a vertical direction (vertical type) from the viewpoint of operability of filling and removing the catalyst. Since the gas-phase catalytic oxidation reaction of the present invention is an exothermic reaction, a system for removing reaction heat from the outside of the reaction tube is generally used. The inner diameter, outer diameter, length and material of the reaction tube, the reaction heat removing means, the reaction heat removing method and the like are not particularly limited, but the inner diameter of the reaction tube is preferably 10 to 50mm and the length thereof is preferably 1 to 6m in consideration of both the heat exchange area for the removal of reaction heat and the pressure loss inside the reaction tube. Since there is a limit in increasing the inner diameter of the reaction tubes 1 in order to remove the reaction heat, the reactor may be of a multi-tube type. The number of reaction tubes in an industrial production facility can be set to several hundreds to several thousands, thereby ensuring the throughput. The reaction tube is not limited as long as it is made of a material having corrosion resistance and heat resistance. As the material of the reaction tube, for example, SUS raw material, particularly SUS316L can be cited.

Conventionally, a uniform catalyst is uniformly packed in a reactor, but in the present invention, the catalyst is packed so that the amount of (d) the alkali metal salt compound to be supported is decreased in order from the inlet side to the outlet side of the fixed-bed tubular reactor. That is, catalyst layers having different amounts of the alkali metal salt compound are packed in a plurality of stages in the reaction tube so that the amounts of the alkali metal salt compound are sequentially decreased along the flow direction of the raw material gas. The number of catalyst layers may be 2 or more, or may be 3 or more. The amount of the alkali metal salt compound to be supported may be set to be continuously decreased (gradually changed). From the viewpoint of operability of catalyst filling in an actual plant, the catalyst layer is preferably 2 layers or 3 layers, and even 2 layers are sufficient for achieving the object of the present invention.

When the catalyst layers (d) having different amounts of the alkali metal salt compound are packed in the reaction tube in a multi-layer manner so that the amounts of the alkali metal salt compound are sequentially reduced, the catalyst layers having a smaller amount of the alkali metal salt compound (g) per 1g of the (e) carrier may be packed sequentially so as to be packed on the outlet side. The amount (g) of the alkali metal salt compound supported by the catalyst layer on the inlet side of the reaction tube is preferably 1.2 to 3.0 times, more preferably 1.3 to 2.4 times, and still more preferably 1.3 to 2.1 times the amount (g) of the alkali metal salt compound supported by the catalyst layer on the outlet side of the reaction tube per 1g of the carrier. The effect of the present invention can be improved by setting the loading amount ratio to 1.2 times or more, while the deterioration of the catalyst can be suppressed by setting the loading amount ratio to 3.0 times or less.

The ratio of the amount of the (d) alkali metal salt compound supported in the catalyst layer is the ratio at the start of the reaction. The amount of the alkali metal salt compound in each catalyst layer changes over a long reaction period of several hundred to several thousand hours. In the case of a vertical reaction tube, the alkali metal salt compound in the upper (inlet side) catalyst layer may move to the lower (outlet side) catalyst layer and may be gradually discharged from the reaction tube. In this case, it is preferable to supply the effluent portion of the alkali metal salt compound to the reactor.

(d) The amount of the component other than the alkali metal salt compound to be supported is usually the same in all the catalyst layers, and may be changed so as to improve the overall reaction efficiency.

The ratio of the lengths of the catalyst layers in the case where the catalyst layer is 2 layers is preferably the reactor inlet side: outlet side 4: 1-1: 4, more preferably the reactor inlet side: exit side 3: 2-1: 4, particularly preferably 3: 2-2: 3.

< production of allyl acetate >

The reaction for producing allyl acetate is preferably carried out in a vapor phase starting from propylene, oxygen and acetic acid. It is preferable to use a fixed bed flow reaction in which the above catalyst is packed in a reaction tube having corrosion resistance, which is advantageous in practical use. The reaction formula is shown as the following formula.

CH₂＝CHCH₃+CH₃COOH+1/2O₂→

CH₂＝CHCH₂OCOCH₃+H₂O

The raw material gas contains propylene, oxygen and acetic acid, and nitrogen, carbon dioxide, a rare gas, or the like may be used as a diluent as necessary.

The raw material gas preferably has a molar ratio of acetic acid: propylene: oxygen gas 1: 1-12: 0.5 to 2.

In the reaction for producing allyl acetate, when water is present in the reaction system, the activity of the catalyst for producing allyl acetate and the maintenance of the activity are remarkably effective. The water vapor is preferably present in the gas supplied to the reaction in a range of 0.5 to 25 vol%.

The gas to be supplied to the reaction is preferably high-purity propylene, but lower saturated hydrocarbons such as methane, ethane, and propane may be mixed in the propylene. The oxygen gas may be supplied in a form diluted with an inert gas such as nitrogen gas or carbon dioxide gas, for example, in a form of air, and when the reaction gas is circulated, it is advantageous to use oxygen gas in a high concentration, preferably 99% by volume or more.

The reaction temperature is not particularly limited. Preferably 100 to 300 ℃, and more preferably 120 to 250 ℃. The reaction pressure is practically advantageous from the viewpoint of facilities in the range of 0.0 to 3.0MPaG (gauge pressure), but is not particularly limited. More preferably in the range of 0.1 to 1.5MPaG (gauge pressure).

In the case of carrying out the reaction by the fixed bed flow-through reaction, the raw material gas is preferably in a normal state at a space velocity: SV of 10-15000 hours^-1Is supplied to the catalyst in the range of 300 to 8000 hours, particularly preferably^-1Is supplied to the catalyst.

Examples

The present invention will be further described below by way of examples and comparative examples, but the present invention is not limited to these descriptions.

PREPARATION EXAMPLE 1 preparation of catalyst A

A spherical silica carrier (sphere diameter 5mm, specific surface area 155 m) was used²Water absorption of 0.85g/g, hereinafter referred to simply as "silica carrier"), and the catalyst A was produced in the following order.

Step 1

4.1L of an aqueous solution containing 199g of sodium chloropalladate and 4.08g of sodium chloroaurate tetrahydrate was prepared as an A-1 solution. To this was added 12L of a silica carrier (bulk density 473g/L, water absorption 402g/L), and the A-1 solution was impregnated and allowed to absorb the entire amount.

Step 2

427g of sodium metasilicate nonahydrate was dissolved in pure water, and the solution was diluted with pure water to a total amount of 8.64L using a measuring cylinder to prepare an A-2 solution. The metal-supporting carrier obtained in step 1 was impregnated with the a-2 solution, and the mixture was allowed to stand at room temperature for 20 hours.

Step 3

300g of hydrazine monohydrate was added to the slurry of the alkali-treated silica carrier obtained in step 2, and the mixture was stirred gradually and then allowed to stand at room temperature for 4 hours. The obtained catalyst was filtered, transferred to a glass column with a stopcock, and washed by passing pure water through the column for 40 hours. Next, drying was performed at 110 ℃ for 4 hours under an air stream to obtain a metal-supported catalyst (A-3).

Step 4

624g of potassium acetate and 90g of copper acetate monohydrate were dissolved in pure water, and the solution was diluted with pure water to a total volume of 3.89L using a measuring cylinder. The metal-supported catalyst (a-3) obtained in step 3 was added thereto so as to absorb the entire amount. Subsequently, the allyl acetate was dried at 110 ℃ for 20 hours under an air stream, thereby obtaining catalyst a for allyl acetate production. (a) The mass ratio of (a) to (b) to (c) to (d) is (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.024: 0.39: 8.5. with respect to the mass ratio, it is based on the mass of the component elements for (a), (b) and (c) and on the mass of the alkali metal salt compound for (d). (d) The amount (g) of the alkali metal salt compound supported on 1g of the (e) carrier was 0.110 g/g.

PREPARATION EXAMPLE 2 preparation of catalyst B

Catalyst B was produced by repeating the procedure of production example 1 except that the amount of potassium acetate was changed from 624g to 396g in step 4. (a) The mass ratio of (a) to (b) to (c) to (d) is (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.024: 0.39: 5.4. with respect to the mass ratio, it is based on the mass of the component elements for (a), (b) and (c) and on the mass of the alkali metal salt compound for (d). (d) The amount (g) of the alkali metal salt compound supported on 1g of the (e) carrier was 0.069 g/g.

< reference examples 1 and 2> evaluation of the Performance of catalysts A and B

10.5mL each of the catalysts A and B obtained in production examples 1 and 2 was uniformly diluted with 31.5mL of a ceramic ball and then packedIn a reaction tube (made of SUS316L, inner diameter 25 mm). At a reaction temperature of 150 ℃ and a reaction pressure of 0.8MPaG (gauge pressure), at a space velocity of 2070 hours^-1The composition of the introduced gas was propylene: oxygen: acetic acid: 35 parts of water: 6: 8: the mixed gas of 23 (volume ratio) generates allyl acetate from propylene, oxygen and acetic acid. Analysis of the reaction was performed 200 hours after the start of the reaction.

As a method for analyzing the reactant, a method of cooling the total amount of the outlet gas passing through the catalyst-packed layer, recovering the total amount of the condensed reaction solution, and analyzing the same by gas chromatography is used. The total amount of non-condensable gas flowing out during the sampling time was measured for the non-condensable gas, and a part thereof was taken out and analyzed by gas chromatography.

Analysis of the condensed reaction solution was carried out by an internal standard method using a FID detector and a capillary column TC-WAX (length: 30m, inner diameter: 0.25mm, thickness: 0.25 μm) using GC-14B manufactured by Shimadzu corporation.

Analysis of uncondensed gas GC-14B (gas sampler MGS-4 for Shimadzu gas chromatography, with a 1mL metering tube) manufactured by Shimadzu corporation was used, and analysis was performed by the absolute calibration curve method using a TCD detector (He carrier gas, current value 100mA), packed column MS-5A IS (3 mm. phi. times.3 m, 60/80 mesh) and Unibeads (3 mm. phi. times.3 m, 60/80 mesh).

The activity of the catalyst was calculated as the mass of allyl acetate produced per unit volume (L) of the catalyst in 1 hour (space-time yield: STY, unit: g/L-cat hr).

The selectivity of allyl acetate was calculated by the following equation.

Allyl acetate selectivity (propylene basis) (%) - [ allyl acetate production amount (mol)/propylene consumption amount (mol) ] x 100

The amount of potassium acetate in the catalyst was quantified as follows: the catalyst was pulverized to prepare a uniform powder, and then molded, and the content (% by mass) of K (potassium) atoms was determined as a quantitative determination by an absolute calibration curve method using fluorescent X-ray analysis (XRF).

The results of reference examples 1 and 2 are shown in table 1. The evaluation 200 hours after the start of the reaction revealed that the catalyst a of reference example 1 had higher activity (STY) than the catalyst B of reference example 2. It can be said that a large amount of potassium acetate supported in the production of allyl acetate exhibits high catalyst activity.

TABLE 1

< example 1>

In a reaction tube having an inner diameter of 34mm, an inert sphere was sequentially packed from the reaction gas inlet side toward the outlet side in a layer length of 0.8m on the upstream side of the catalyst on the reaction gas inlet side, a catalyst A having a large amount of potassium acetate and a high activity was packed in a layer length of 3.3m, and a catalyst B having a small amount of potassium acetate and a low activity was packed in a layer length of 2.2 m. At a space velocity of 2000 hours^-1A raw material gas having a composition shown in Table 2 was passed through the reactor, and the reaction was continuously carried out at a reaction temperature of 160 ℃ and a reaction pressure of 0.75MPaG (gauge pressure) for 8000 hours. After the reaction was completed, the catalyst was divided into 3: 2, the catalyst C was taken out from the inlet side of the reaction tube and the catalyst D was taken out from the outlet side of the reaction tube. Fig. 1A shows the filling position of the catalyst of example 1. At the start of the reaction, (d) the alkali metal salt compound (potassium acetate) on the catalyst a (inlet side) was supported at 0.1099g/g per 1g of the (e) carrier, and (d) the alkali metal salt compound (potassium acetate) on the catalyst B (outlet side) was supported at 0.069g/g per 1g of the (e) carrier, and the ratio of the supported amount of potassium acetate was 1.59(═ 0.1099/0.069). For the catalysts C and D, performance evaluation was performed after 8000 hours had elapsed under evaluation conditions described later. Table 4 shows the results of example 1 (as a whole).

TABLE 2

Composition (I)	Content (volume%)
		Acetic acid	8
Propylene (PA)	35
		Oxygen gas	6
Water (W)	18
		Inert gases such as nitrogen	33

< comparative example 1>

The same reaction as in example 1 was carried out except that all the catalysts to be filled were the catalyst a and the catalyst a was filled so that the layer length thereof was 5.5 m. After the reaction was completed, the catalyst was divided into 3: 2, the catalyst E was taken out from the reactor so that the catalyst E was on the inlet side of the reactor and the catalyst F was on the outlet side of the reactor. Fig. 1B shows the filling position of the catalyst of comparative example 1. The results are shown in Table 4.

< comparative example 2>

The reaction was carried out in the same manner as in example 1 except that the catalyst B was packed in a layer having a length of 3.3m from the reaction gas inlet side and the catalyst a was packed in a layer having a length of 2.2 m. After the reaction was completed, the catalyst was divided into 3: 2, catalyst G was taken out from the reactor inlet side and catalyst H was taken out from the reactor outlet side. Fig. 1C shows the filling position of the catalyst of comparative example 2. The results are shown in Table 4.

< evaluation of the Properties of catalysts C to H >

The catalysts obtained in example 1 and comparative examples 1 and 2 were used10.5mL of each of C to H was uniformly diluted with 31.5mL of a ceramic ball, and the resulting mixture was packed in a reaction tube (made of SUS316L, inner diameter: 25 mm). At space velocity of 2070 hours^-1A raw material gas having a composition shown in Table 3 was passed through the reactor, and oxidation reaction was carried out at a reaction temperature of 160 ℃ and a reaction pressure of 0.8MPaG (gauge pressure) for 4 hours. The results are shown in Table 4.

TABLE 3

Composition (I)	Content (volume%)
		Acetic acid	8
Propylene (PA)	35
		Oxygen gas	7
Water (W)	23
		Nitrogen gas	27

TABLE 4

As is clear from table 4, in example 1, the allyl acetate STY was larger in the whole after 8000 hours of reaction than in comparative example 1 in which the reaction tube was uniformly filled with the catalyst and comparative example 2 in which the amount of potassium acetate supported was reversely filled, and the catalyst performance was less degraded than that in the whole reaction tube at the beginning of the reaction (200 hours). It is also found that catalyst D of example 1 has a smaller amount of potassium acetate and a higher allyl acetate activity than catalyst F of comparative example 1. From these results, it is found that, in comparison with the case where the reaction is performed by uniformly filling the catalyst of the same specification, when the reaction is performed by filling the catalyst so that the amount of potassium acetate supported by the catalyst is decreased in order from the inlet side to the outlet side of the reactor as in the present invention, the distribution of potassium acetate in the flow direction of the raw material gas in the reaction tube can be controlled more uniformly, and the decrease in the catalytic activity with time can be suppressed.

Industrial applicability

The present invention provides a method for producing allyl acetate having an improved catalyst life, which is industrially useful because it can be used for the efficient production of allyl acetate.

Claims

1. A process for producing allyl acetate, characterized by supplying propylene, oxygen and acetic acid as raw material gases to a fixed-bed tubular reactor packed with an allyl acetate-producing catalyst comprising (a) palladium, (b) gold, (c) a 4 th-cycle metal compound having at least 1 element selected from the group consisting of copper, nickel, zinc and cobalt, (d) an alkali metal salt compound and (e) a carrier, and producing allyl acetate by a vapor-phase catalytic oxidation reaction,

in the above production method, 2 or more catalyst layers containing the catalyst for producing allyl acetate are disposed along the flow direction of the raw material gas in the reaction tube of the fixed-bed tubular reactor so that the amount of the (d) alkali metal salt compound supported on the (e) carrier decreases in the order from the inlet side to the outlet side of the fixed-bed tubular reactor, and the amounts of the (d) alkali metal salt compound in the catalysts for producing allyl acetate contained in the respective catalyst layers are different.

2. A process for producing allyl acetate according to claim 1, wherein the amount of (d) the alkali metal salt compound supported on 1g of the (e) carrier in the catalyst layer on the entry side of the reaction tube is 1.2 to 3.0 times the amount of (d) the alkali metal salt compound supported on 1g of the (e) carrier in the catalyst layer on the exit side, wherein the amount of (d) the alkali metal salt compound is in g.

3. The method for producing allyl acetate according to claim 1 or 2, wherein the reaction tube is a straight tube, the catalyst layer is 2 layers, and the ratio of the length of the catalyst layer on the inlet side to the length of the catalyst layer on the outlet side of the reaction tube in the flow direction of the raw material gas is 4:1 to 1: 4.

4. The method for producing allyl acetate according to claim 1 or 2, wherein the fixed-bed tubular reactor is a multitubular type.

5. The method for producing allyl acetate according to claim 1 or 2, wherein the alkali metal salt compound (d) is at least 1 selected from the group consisting of potassium acetate, sodium acetate, and cesium acetate.

6. The method for producing allyl acetate according to claim 1 or 2, wherein the (c) 4 th cycle metal compound is a compound having copper or zinc.

7. The method for producing allyl acetate according to claim 1 or 2, wherein the (c) 4 th cycle metal compound is copper acetate.

8. The method for producing allyl acetate according to claim 1 or 2, wherein the catalyst for producing allyl acetate has a mass ratio of (a) palladium, (b) gold, (c) the 4 th cycle metal compound to (d) the alkali metal salt compound in all the catalyst layers that is (a): (b) the method comprises the following steps (c) The method comprises the following steps (d) 1: 0.00125-22.5: 0.02-90: 0.2 to 450.